The present invention relates to bone cement mixing apparatuses. More particularly, the present invention relates to a bone cement mixing apparatus for mixing bone cement in the presence of a vacuum.
It is necessary in many orthopedic surgical procedures to employ a cement or grouting type agent, such as for attaching artificial joint implants, repairing or forming joints in bones, or other forms of orthopedic work. The type of cement generally used for these purposes are self-curing resins formed from the blending of a wide variety of liquid monomers or comonomers with powdered polymers or copolymers to form a viscous admixture to be used as the grouting agent. The admixture of the powder and liquid components develops a quick setting material and preparation of the cement usually occurs directly within the operating theater just prior to use.
It is known to add a monomer to dry bone cement via a monomer delivery apparatus. See for example, U.S. patent application Ser. No. 09/293,396, filed Apr. 16, 1999, entitled Monomer Delivery Device for Bone Cement Delivery System, the disclosure of which is hereby incorporated by reference. In such an apparatus, the monomer agent and the bone cement are mixed in the presence of a vacuum. The mixture being subjected to the vacuum serves a dual role. First, the vacuum serves to evacuate fumes the monomer used in the mixture may produce. Second, the vacuum actively reduces the amount of air bubbles or vapor pockets in the mixture during the mixing process.
According to the present invention bone cement mixing apparatus is provided that comprises a bowl, a lid that is removably attached to the bowl, a crank extending through and removably attached to the lid, and a blade positioned in the bowl. The lid includes a sealable monomer delivery port. In addition, the blade is attached to the crank such that the blade rotates with the crank. In preferred embodiments, the blade is non-concentrically shaped and has a vane attached thereon to increase the mixing and shearing action.
In a further embodiment of the present invention, a vacuum outlet may be attached to either the lid, handle, or bowl. The outlet attaches to a vacuum hose that routes air and vapors away from the mixing bowl. In a still further embodiment, the mixing bowl includes a plurality of intermittent shims placed about the circumference of the bowl so that the outer edge of the lid having several annular intermittent flanges cooperate with each intermittent shim on the bowl. In an additional embodiment, the mixing blade contours about one quarter the circumference of the bowl. The blade may also include an angled shoulder blade.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.